1. Field of the Invention
The present invention relates to a glass run for attachment to an inner periphery of a door frame of a motor vehicle for guiding a door glass as it is raised and lowered.
2. Description of Related Art
As shown in FIG. 1, a glass run 10 is attached to an inner periphery of a door frame 12 of a vehicle door 14 for guiding a door glass 16 which is raised and lowered, and sealing between the door glass 16 and the door frame 12. FIGS. 2 and 3 show examples of the conventional glass run 10 for attachment into a channel 18 provided along the inner periphery of the door frame 12. The glass run 10 is formed by connecting extruded straight parts with molded parts into a configuration conforming to that of the door frame 12.
In addition, a door weather strip (not shown) is attached to an outer periphery of the door frame 12, and/or an opening trim weather strip (not shown) is attached to a flange provided in a door opening portion of a vehicle body, thereby sealing between the vehicle door 14 and the vehicle body.
The glass run 10 includes an outside wall 20, an inside wall 22 and a bottom wall 24, and has a generally U-shaped cross-section. An outside seal lip 26 and an inside seal lip 28 extend from open ends of the outside wall 20 and the inside wall 22 towards an interior of the glass run 10. When the glass run 10 is attached into the channel 18, outer surfaces of the outside wall 20, the inside wall 22 and the bottom wall 24 contact the inner surfaces of the channel 18.
When the door glass 16 is raised, it slides into the interior of the glass run 10, and an end of the door glass 16 is sealed and held by the outside seal lip 26 and the inside seal lip 28 (Publication of unexamined patent application No. 2000-25462, pages 2-3, FIG. 2).
The conventional glass run 10, however, exhibits the following problem. Namely, while a motor vehicle is running at high speeds, the door glass 16 may be drawn outwardly, or may vibrate due to vibrations of the vehicle body, thereby pressing the outside seal lip 26 against the outside wall 20 (Publication of unexamined patent application No. 2002-19473, pages 3-5, FIG. 1(b)).
Accordingly, the outside seal lip 26 may contact an inner surface of the outside wall 20 closely, and is difficult to separate therefrom after the door glass 16 stops pressing the outside seal lip 26. Consequently, sealing between the door glass 16 and the outside seal lip 26, or holding of the door glass 16 with the outside seal lip 26 may become insufficient.
To improve the slidability of the inner surface of the outside wall 20 relative to an end of the outside seal lip 26, the inner surface of the outside wall 20 may be coated with a low friction material such as silicone coating, etc. But, the coating work is troublesome, because the outside seal lip 26 must be turned up upon coating the inner surface of the outside wall 20.
On the other hand, where the coating condition of the low friction material varies, noise may be generated when the door glass 16 shifts inwardly, and the outside seal lip 26 which has contacted the outside wall 20 rapidly separates from insufficiently coated area of the inner surface of the outside wall 20.
In addition, as shown in FIG. 3, where an end 27 of the outside seal lip 26, projects toward the outside wall 20, it contacts and presses the inner surface of the outside wall 20 earlier than the remaining portion of the outside seal lip 26, and accordingly, so-called “bottoming” occurs earlier, as compared with other flat outside seal lips. Consequently, a reaction force from the outside wall 20 increases to press the outside seal lip 26 against the door glass 16 strongly, thereby increasing the sliding resistance between the door glass 16 and the outside seal lip 26. As a result, the door glass 16 may not be raised and lowered smoothly, or there may be generated noise, etc. due to rubbing of the door glass 16 and the outside seal lip 26.